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P16
p16 (also known as p16INK4a, cyclin-dependent kinase inhibitor 2A, CDKN2A, multiple tumor suppressor 1 and numerous other synonyms), is a protein that slows cell division by slowing the progression of the cell cycle from the G1 phase to the S phase, thereby acting as a tumor suppressor. It is encoded by the ''CDKN2A'' gene. A deletion (the omission of a part of the DNA sequence during replication) in this gene can result in insufficient or non-functional p16, accelerating the cell cycle and resulting in many types of cancer. p16 can be used as a biomarker to improve the histological diagnostic accuracy of grade 3 cervical intraepithelial neoplasia (CIN). p16 is also implicated in the prevention of melanoma, oropharyngeal squamous cell carcinoma, cervical cancer, vulvar cancer and esophageal cancer. p16 was discovered in 1993. It is a protein with 148 amino acids and a molecular weight of 16 kDa that comprises four ankyrin repeats. The name of p16 is derived from its molecula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CDKN2A
CDKN2A, also known as cyclin-dependent kinase inhibitor 2A, is a gene which in humans is located at chromosome 9, band p21.3. It is ubiquitously expressed in many tissues and cell types. The gene codes for two proteins, including the INK4 family member p16 (or p16INK4a) and p14arf. Both act as tumor suppressors by regulating the cell cycle. p16 inhibits cyclin dependent kinases 4 and 6 ( CDK4 and CDK6) and thereby activates the retinoblastoma (Rb) family of proteins, which block traversal from G1 to S-phase. p14ARF (known as p19ARF in the mouse) activates the p53 tumor suppressor. Somatic mutations of CDKN2A are common in the majority of human cancers, with estimates that CDKN2A is the second most commonly inactivated gene in cancer after p53. Germline mutations of CDKN2A are associated with familial melanoma, glioblastoma and pancreatic cancer. The ''CDKN2A'' gene also contains one of 27 SNPs associated with increased risk of coronary artery disease. Structure Gene The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyclin-dependent Kinase 4
Cyclin-dependent kinase 4 also known as cell division protein kinase 4 is an enzyme that in humans is encoded by the ''CDK4'' gene. CDK4 is a member of the cyclin-dependent kinase family. Function The protein encoded by this gene is a member of the Ser/Thr protein kinase family. This protein is highly similar to the gene products of ''S. cerevisiae'' cdc28 and ''S. pombe'' cdc2. It is a catalytic subunit of the protein kinase complex that is important for cell cycle G1 phase progression. The activity of this kinase is restricted to the G1-S phase, which is controlled by the regulatory subunits D-type cyclins and CDK inhibitor p16INK4a. This kinase was shown to be responsible for the phosphorylation of retinoblastoma gene product ( Rb). Ser/Thr-kinase component of cyclin D-CDK4 (DC) complexes that phosphorylate and inhibit members of the retinoblastoma (RB) protein family including RB1 and regulate the cell-cycle during G1/S transition. Phosphorylation of RB1 allows dissociati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
P53 (protein)
p53, also known as Tumor protein P53, cellular tumor antigen p53 (UniProt name), or transformation-related protein 53 (TRP53) is a regulatory protein that is often mutated in human cancers. The p53 proteins (originally thought to be, and often spoken of as, a single protein) are crucial in vertebrates, where they prevent cancer formation. As such, p53 has been described as "the guardian of the genome" because of its role in conserving stability by preventing genome mutation. Hence ''TP53'' ''italics'' are used to denote the ''TP53'' gene name and distinguish it from the protein it encodes is classified as a tumor suppressor gene. The name p53 was given in 1979 describing the apparent molecular mass; SDS-PAGE analysis indicates that it is a 53-kilodalton (kDa) protein. However, the actual mass of the full-length p53 protein (p53α) based on the sum of masses of the amino acid residues is only 43.7 kDa. This difference is due to the high number of proline residues in the protein, w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
P14arf
p14ARF (also called ARF tumor suppressor, ARF, p14ARF) is an alternate reading frame protein product of the ''CDKN2A'' locus (i.e. ''INK4a''/''ARF'' locus). p14ARF is induced in response to elevated mitogenic stimulation, such as aberrant growth signaling from MYC and Ras (protein). It accumulates mainly in the nucleolus where it forms stable complexes with NPM or Mdm2. These interactions allow p14ARF to act as a tumor suppressor by inhibiting ribosome biogenesis or initiating p53-dependent cell cycle arrest and apoptosis, respectively. p14ARF is an atypical protein, in terms of its transcription, its amino acid composition, and its degradation: it is transcribed in an alternate reading frame of a different protein, it is highly basic, and it is polyubiquinated at the N-terminus. Both p16INK4a and p14ARF are involved in cell cycle regulation. p14ARF inhibits mdm2, thus promoting p53, which promotes p21 activation, which then binds and inactivates certain cyclin- CDK complexes, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melanoma
Melanoma, also redundantly known as malignant melanoma, is a type of skin cancer that develops from the pigment-producing cells known as melanocytes. Melanomas typically occur in the skin, but may rarely occur in the mouth, intestines, or eye (uveal melanoma). In women, they most commonly occur on the legs, while in men, they most commonly occur on the back. About 25% of melanomas develop from moles. Changes in a mole that can indicate melanoma include an increase in size, irregular edges, change in color, itchiness, or skin breakdown. The primary cause of melanoma is ultraviolet light (UV) exposure in those with low levels of the skin pigment melanin. The UV light may be from the sun or other sources, such as tanning devices. Those with many moles, a history of affected family members, and poor immune function are at greater risk. A number of rare genetic conditions, such as xeroderma pigmentosum, also increase the risk. Diagnosis is by biopsy and analysis of any skin lesion ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ankyrin Repeat
The ankyrin repeat is a 33-residue motif in proteins consisting of two alpha helices separated by loops, first discovered in signaling proteins in yeast Cdc10 and ''Drosophila'' Notch. Domains consisting of ankyrin tandem repeats mediate protein–protein interactions and are among the most common structural motifs in known proteins. They appear in bacterial, archaeal, and eukaryotic proteins, but are far more common in eukaryotes. Ankyrin repeat proteins, though absent in most viruses, are common among poxviruses. Most proteins that contain the motif have four to six repeats, although its namesake ankyrin contains 24, and the largest known number of repeats is 34, predicted in a protein expressed by ''Giardia lamblia''. Ankyrin repeats typically fold together to form a single, linear solenoid structure called ankyrin repeat domains. These domains are one of the most common protein–protein interaction platforms in nature. They occur in a large number of functionally diverse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromosome 9 (human)
Chromosome 9 is one of the 23 pairs of chromosomes in humans. Humans normally have two copies of this chromosome, as they normally do with all chromosomes. Chromosome 9 spans about 138 million base pairs of nucleic acids (the building blocks of DNA) and represents between 4.0 and 4.5% of the total DNA in cells. Genes Number of genes These are some of the gene count estimates of human chromosome 9. Because researchers use different approaches to genome annotation, their predictions of the number of genes on each chromosome varies (for technical details, see gene prediction). Among various projects, the collaborative consensus coding sequence project ( CCDS) takes an extremely conservative strategy. So CCDS's gene number prediction represents a lower bound on the total number of human protein-coding genes. Gene list The following is a partial list of genes on human chromosome 9. For a complete list, see the link in the infobox on the right. Diseases and disorders The follo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcription (genetics)
Transcription is the process of copying a segment of DNA into RNA. The segments of DNA transcribed into RNA molecules that can encode proteins are said to produce messenger RNA (mRNA). Other segments of DNA are copied into RNA molecules called non-coding RNAs (ncRNAs). mRNA comprises only 1–3% of total RNA samples. Less than 2% of the human genome can be transcribed into mRNA ( Human genome#Coding vs. noncoding DNA), while at least 80% of mammalian genomic DNA can be actively transcribed (in one or more types of cells), with the majority of this 80% considered to be ncRNA. Both DNA and RNA are nucleic acids, which use base pairs of nucleotides as a complementary language. During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, antiparallel RNA strand called a primary transcript. Transcription proceeds in the following general steps: # RNA polymerase, together with one or more general transcription factors, binds to promoter DNA ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exon
An exon is any part of a gene that will form a part of the final mature RNA produced by that gene after introns have been removed by RNA splicing. The term ''exon'' refers to both the DNA sequence within a gene and to the corresponding sequence in RNA transcripts. In RNA splicing, introns are removed and exons are covalently joined to one another as part of generating the mature RNA. Just as the entire set of genes for a species constitutes the genome, the entire set of exons constitutes the exome. History The term ''exon'' derives from the expressed region and was coined by American biochemist Walter Gilbert in 1978: "The notion of the cistron… must be replaced by that of a transcription unit containing regions which will be lost from the mature messengerwhich I suggest we call introns (for intragenic regions)alternating with regions which will be expressedexons." This definition was originally made for protein-coding transcripts that are spliced before being translated. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Splicing (genetics)
RNA splicing is a process in molecular biology where a newly-made precursor messenger RNA (pre-mRNA) transcript is transformed into a mature messenger RNA (mRNA). It works by removing all the introns (non-coding regions of RNA) and ''splicing'' back together exons (coding regions). For nuclear-encoded genes, splicing occurs in the nucleus either during or immediately after transcription. For those eukaryotic genes that contain introns, splicing is usually needed to create an mRNA molecule that can be translated into protein. For many eukaryotic introns, splicing occurs in a series of reactions which are catalyzed by the spliceosome, a complex of small nuclear ribonucleoproteins (snRNPs). There exist self-splicing introns, that is, ribozymes that can catalyze their own excision from their parent RNA molecule. The process of transcription, splicing and translation is called gene expression, the central dogma of molecular biology. Splicing pathways Several methods of RNA splicin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Isoform
A protein isoform, or "protein variant", is a member of a set of highly similar proteins that originate from a single gene or gene family and are the result of genetic differences. While many perform the same or similar biological roles, some isoforms have unique functions. A set of protein isoforms may be formed from alternative splicings, variable promoter usage, or other post-transcriptional modifications of a single gene; post-translational modifications are generally not considered. (For that, see Proteoforms.) Through RNA splicing mechanisms, mRNA has the ability to select different protein-coding segments ( exons) of a gene, or even different parts of exons from RNA to form different mRNA sequences. Each unique sequence produces a specific form of a protein. The discovery of isoforms could explain the discrepancy between the small number of protein coding regions genes revealed by the human genome project and the large diversity of proteins seen in an organism: different ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
